SMN2 and amyotrophic lateral sclerosis: The involved genotyping methodology included linkage analysis for those with trinucleotide expansion disorders (SCA3, SCA6, and Huntington’s disease) in 21 embryos from 4 patients, and ARMS-qPCR method for those with point mutations (Charcot–Marie–Tooth 2E, ALS, and FAP) and small deletions (SMA) (although SMA is a gene dosage disorder, SMN2 has a small deletion in exon 7 compared to SMN1 that can be used in PGD to elucidate the existence of SMN1 and thus exclude the affected embryos) in 38 embryos from 6 patients.